This invention relates to optical circuit modules in general, and more particularly to methods and apparatus for testing the same.
Optical circuit modules, such as those used in fiberoptic telecommunications products, typically require substantial testing (including characterization) during manufacture and before they are released to the field.
Standard practice for the testing of optical circuit modules, and in particular for the testing of the optical components of those modules, is for a single device-under-test (xe2x80x9cDUTxe2x80x9d) to be examined at a time, using a dedicated set of test equipment.
Unfortunately, however, the dedicated set of test equipment (or xe2x80x9ctest packxe2x80x9d) is generally a relatively complex array of instrumentation controlled by a dedicated computer or controller. As a result, the cost of each test pack typically costs between about $250,000 and $800,000. Furthermore, depending on the specific tests which are to be run on the DUT, each DUT typically requires between about 15 minutes to several hours to complete its testing. Thus it will be seen that manufacturers who must produce large numbers of these optical circuit modules must invest large amounts in replicating each expensive test pack to ensure sufficient product throughput.
In addition to the foregoing, in many cases the DUT should, ideally, be tested under a variety of different operating temperatures. This generally requires that the DUT be brought to (and stabilized at) a first temperature, tested, then brought to a second temperature, tested, etc. until the DUT has been tested through the full range of temperatures desired. In view of the substantial delays generally associated with bringing the DUT xe2x80x9cup to temperaturexe2x80x9d (e.g., it can often take up to 30 minutes to bring the DUT to, and stabilize the DUT at, a given temperature), this can dramatically increase the time necessary to test each DUT and reduce the throughput for each test pack, thereby reducing productivity, requiring the provision of additional expensive test packs, etc.
In response to these issues, a novel method and apparatus has been developed for testing optical circuit modules. More particularly, with the present invention, a given test pack is adapted to xe2x80x9csimultaneouslyxe2x80x9d test a plurality of DUT""s, by simultaneously apply a given optical signal to each of the plurality of DUT""s and allowing each of the DUT""s to simultaneously undergo its own testing; the test pack then serially queries each of the DUT""s to obtain test results and, if desired, can provide feedback to one or more of the DUT""s, whereby the DUT""s can be calibrated with the assistance of the test pack.
In one preferred form of the invention, all of the plurality of DUT""s simultaneously undergoing testing on a given test pack are housed in a single environmental enclosure, permitting all of the DUT""s to be simultaneously brought xe2x80x9cup to temperaturexe2x80x9d so as to increase testing throughput.